A study of the acoustic backscattering produced by an array of scattering spheres fixed to a fishing net is reported. The system enhances net detection and also allows net identijcation by using a method in which the echogram is arranged to resemble a commercial bar-code. A simplified theoretical model has been developed to study the interference due to echo formation. This model establishes the relations between system geometry (target dimensions, scatterer separation and net depth) and sonar performance (directivity, pulse length. pulse repetition rate, wavelength. and ship speed), getting a better svstem response. Experimental tests have been realized in a water tank in good agreement with bar code gillnet identification provided by the theoretical model. A sea survey in the Mediterranean sea has been carried out. It has been placed a gillnet with an array of plastic hollow spheres attached at the headline of the net. Several measurements were taken with o side scan sonar to detect the net and identify the associated bar code.